Silencer with angled tuning tube leading to helmholtz resonator



March 25, 1969 R. L. FISCHER SILENCER WITH ANGLED TUNING TUBE LEADING TO HELMHOLTZ RESONATOR Filed Dec. 21, 1967 Y 5 \A L R Q kw N \W \W NE mmm w w m mm m vw m M R w Q Q m ML\ Q lw U m 7? 3 f F v a m MZ 1 1 7WY 071B United States Patent 3,434,565 SILENCER WITH ANGLED TUNING TUBE LEAD- ING T HELMHOLTZ RESONATOR Richard L. Fischer, Jackson, Mich., assignor to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Dec. 21, 1967, Ser. No. 692,361 Int. Cl. F01n 1/00 US. Cl. 181-48 1 Claim ABSTRACT OF THE DISCLOSURE Low frequencies are silenced in an exhaust gas mufiler by means of a resonator chamber connected to the exhaust gas stream by a tuning tube which is bent at a right angle, to obtain a maximum length of tuning tube in a minimum length of muflier.

Background of the invention In silencing the exhaust gases of an internal combustion engine by means of a muffler construction, very difiicult problems are caused by relatively low frequency sound. These require tuned constructions and the lower the frequency the larger the volume and length of tuning tube required for silencing. Both these factors make for a large size mufiler which is ditficult to position under modern low slung automobiles.

Brief summary of the invention It is the purpose of this invention to provide a mufiler construction which includes means for silencing low frequencies that is constructed to conserve space and reduce the overall size of the muffler as compared with units now in use. i

The invention accomplishes this purpose by bending the tuning tube so that the projected length of the tube is considerably less than the actual length of the tube, thus reducing the length of the space in a mufller required to accommodate the tube. Preferably the tuning tube has a right angle bend in it and the inlet end is connected to the gas flow passage and the outlet end dead ends in a resonator chamber.

Description 0 the drawings FIGURE 1 is a longitudinal cross section through a mufiier embodying one form of the invention; and

FIGURE 2 is a longitudinal cross section through a muffler embodying another form of the invention.

Description of the invention The mufiler 1 of FIGURE 1 has an oval outer shell 3 which is closed at one end by an inlet header 5 and at the other end by an outlet header 7. An inlet bushing 9 is supported in the inlet header 5 and an outlet bushing 11 is supported in the outlet header 7.'A straightthrough gas flow passage tube 13 is supported at opposite ends in the bushings 9 and 11 so that gas can flow straight through the shell 3.

Transverse partitions 15, 17, and 19 divide the space within the shell 3 into a series of chambers 21, 23, 25, and 29. The gas flow tube 13 has a louver patch 31 opening into the chamber 21 and a second louver patch 33 opening into the chamber 29.

In accordance with the invention, a tuning tube 35 having an upstream section 37 and a downstream section 39 which extend at right angles to each other is connected around an opening 41 in the wall of pipe 13 so that it is in full acoustic communication with gas "ice flowing through the pipe. The downstream section 39 is supported by an annular flange 43 formed in the partition 15 and opens into the chamber 23, this opening comprising the only inlet and outlet for the chamber 23. The chamber 25 is also connected to the tube 13 by means of a right angle type tuning tube 45 in accordance with the invention which includes a downstream section 47 and an upstream section 49 extending at right angles to it. The section 49 is connected around an opening 51 in the sidewall of the tube 13 and the section 47 extends through annular flanges 53 and 55 formed in the partitions 15 and 17 respectively.

In operation, gas flowing from left toright through the tube 13 is subjected to a medium to high frequency sound attenuating action by virtue of the louver patches 31 and 33 acting in conjunction with the chambers 21 and 29. Lower frequencies of a predetermined level are silenced by the Helmholtz resonator constructions comprising the chamber 23 and the tuning tube 35 and the chamber 25 with the tuning tube 45. Because the tuning tubes 35 and 45 are bent at right angles their effective length in the longitudinal direction is considerably less than their developed or acoustically efiective length. Accordingly, lower frequencies may be attenuated by means of this construction for a given length muflier than with mufiler arrangements now being used.

The muffler 101 of FIGURE 2 is almost identical in construction to the mufiler 1, hence the same parts and features are given the same reference numbers. The significant difference is the elimination of the tuning tube 45 and the substitution of a more conventional tuning tube arangement. In the mufi ier 101 there is a tuning tube 103 that is supported in an annular neck 105 in the partition 15 and a tuning tube 107 that is supported in an annular neck 109 in the position 17. Tuning tubes 103 and 107 in conjunction with the chambers 23 and 25 provide a compound resonator structure while the tuning tube 103 in conjunction with the tuning tube 35 and the chamber 23 provide a double tuner enabling the chamber 23 to attenuate two dilferent frequencies.

Modifications may be made without departing from the spirit and scope of this invention.

What is claimed is:

1. An exhaust gas muffler comprising an elongated tubular casing having an inlet at one end and an outlet at the other end, a plurality of transverse partitions extending across the Width of the casing and subdividing it into a plurality of chambers, means in the casing providing a gas flow passage connecting said inlet and outlet and including a conduit extending through a pair of chambers, the wall of said conduit being inperforate in the first of said chambers and having a patch of louvers opening into the second of said chambers so that said second chamber acts to attenuate medium to high frequency sounds, a tuning tube having first and second portions extending at substantially a right angle to each other, said tuning tube first portion being secured to and opening into said conduit in said second chamber at a location upstream of said louver patch and said first portion extending at substantially a right angle to said conduit, said tuning tube second portion extending in a downstream direction and through a partition and opening into said first chamber, the part of said tuning tube in said second chamber being imperforate, said tuning tube and said first chamber being acoustically interrelated to provide a Helmholtz resonator for silencing a predetermined frequency, lower than that attenuated by said second chamber.

(References on following page) References Cited UNITED STATES PATENTS Bourne.

Haas 18148 Bourne.

Wilson 18148 Powers 18148 Powers 181--54 XR ROBERT S.

FOREIGN PATENTS 7/ 1961 Austria. 1/ 1963 Canada. 7/ 1938 France. 8/1964 France.

WARD, JR., Primary Examiner.

US. Cl. XJR.

Patent No. 3 ,434 ,565 March 25 1969 Richard L. Fischer ears in the above identified It is certified that error app ere'by corrected as patent and that said Letters Patent are h shown below:

" should read partition Column 2, line 35, "position Column line 51, "inperforate" should read imperforate 3 line 3, 2,075,263 3/1937 Bourne" should read 1:9S4,516 4/1934 Bourne 181-48 Signed and sealed this 14th day of April 1970:

(SEAL) Attest:

WILLIAM E. SCHUYLER,

Edward M. Fletcher, Jr.

Commissioner of Pate! Attesting Officer 

